Chapter 4

DOSIMETRY ANALYSIS OF PARTICIPANTS IN PROJECT TRINITY

This chapter summarizes the radiation doses received by participants in various activities during Project TRINITY. The sources of this dosimetry information are the safety and monitoring report for personnel at TRINITY, which includes a compilation of film badge readings for all participants up to 1 January 1946, and film badge data from the records of the Reynolds Electrical and Engineering Company, which contain readings through 1946 (1; 16). These sources list individual participants with their cumulative gamma radiation exposures.

4.1 FILM BADGE RECORDS

During TRINITY, the film badge was the primary device used to measure the radiation dose received by individual participants. The site monitoring plan indicates that film badges were to be issued to participants. The film badge was normally worn at chest level on the outside of clothing and was designed to measure the wearer's exposure to gamma radiation from external sources. These film badges were insensitive to neutron radiation and did not measure the amount of radioactive material that might have been inhaled or ingested (1).

Personnel from the Medical Group had responsibility for issuing, receiving, processing, and interpreting film badges for Project TRINITY. The Site Monitoring Group compiled the film badge records for both onsite and offsite personnel. Radiological safety personnel and military police recorded the names and identification numbers of individuals as they entered the test area. This information was recorded in an entry logbook and on a personal exposure data card. Upon leaving the test area, individuals returned their film badges to the check station. When the film badges were processed and interpreted, the reading was entered on the individuals exposure data card. In this manner, the number of times an individual entered the test area and his cumulative exposure history were recorded and maintained (1).

4.2 GAMMA RADIATION EXPOSURE

The safety and monitoring report lists film badge readings for about 700 individuals who participated in Project TRINITY from 16 July 1945 to 1 January 1946 (1). This list includes both military and nonmilitary personnel who were involved with the TRINITY operation and postshot activities. However, records are available for only 44 of the 144 to 160 members of the evacuation detachment (1). In addition, some of these film badge listings may be for personnel who were only peripherally involved with TRINITY activities, such as family members and official guests who visited the site.

According to the safety and monitoring report, by 1 January 1946, 23 individuals had received cumulative gamma exposures greater than 2 but less than 4 roentgens. An additional 22 individuals received gamma exposures between 4 and 15 roentgens. Personnel who received gamma exposures exceeding 2 roentgens represent less than six percent of the Project TRINITY participants with recorded exposures. As described below, these exposures generally resulted when personnel approached ground zero several times (1).

Information is available regarding the activities of some of these personnel. One of the drivers of the earth-sampling group's lead-lined tank, an Army sergeant who traveled three times to ground zero, received an exposure of 15 roentgens. A second tank driver, also an Army sergeant, received an exposure of 3.3 roentgens. Three members of the earth-sampling group, all of whom traveled in the tank to ground zero, received exposures of 10, 7.5, and 5 roentgens. An Army photographer who entered the test area six times between 23 July and 20 October received 12.2 roentgens (1).

Four individuals involved with excavating the buried supports of the TRINITY tower from 8 October to 10 October 1945 received gamma exposures ranging from 3.4 to 4.7 roentgens. Film badge readings for this three-day period indicate that the two individuals who operated mechanical shovels received 3.4 and 4.3 roentgens, while the two who supervised and monitored the excavation received exposures of 4.2 and 4.7 roentgens. The individual receiving 4.7 roentgens during the excavation operation had received 1.3 roentgens from a previous exposure, making his total exposure 6 roentgens (1).

An Army captain who accompanied all test and observer parties into the ground zero area between 1 September and 11 October 1945 received a total gamma exposure of 2.6 roentgens (1). The activities and times of exposure are not known for other personnel with exposures over 2 roentgens.

According to the dosimetry records for 1946, about 115 people visited the test site that year. No one ventured inside the fence surrounding ground zero, and no one received an exposure greater than 1 roentgen (1; 16).

REFERENCE LIST

The following list of references represents the documents consulted in preparation of the Project TRINITY volume.

AVAILABILITY INFORMATION

An availability statement has been included at the end of the reference citation for those readers who wish to read or obtain copies of source documents. Availability statements were correct at the time the bibliography was prepared. It is anticipated that many of the documents marked unavailable may become available during the declassification review process. The Coordination and Information Center (CIC) and the National Technical Information Service (NTIS) will be provided future DNA-WT documents bearing an EX after the report number.

Source documents bearing an availability statement of CIC may be reviewed at the following address:

Department of Energy Coordination and Information Center (Operated by Reynolds Electrical & Engineering Co., Inc.) ATTN: Mr. Richard V. Nutley 2753 S. Highland P.O. Box 14100 Las Vegas, Nevada 89114

Phone: (702) 734-3194 FTS: 598-3194

Source documents bearing an availability statement of NTIS may be purchased from the National Technical Information Service. When ordering by mail or phone, please include both the price code and the NTIS number. The price code appears in parentheses before the NTIS order number.

National Technical Information Service 5285 Port Royal Road Springfield, Virginia 22161 Phone: (703) 487-4650 (Sales Office)

Additional ordering information or assistance may be obtained by writing to the NTIS, Attention: Customer Service, or by calling (703) 487-4660.

PROJECT TRINITY REFERENCES

*Available from NTIS; order number appears before the asterisk. **Available at CIC. ***Not available, see Availability Information page. ****Requests subject to Privacy Act restrictions.

1. Aebersold, Paul. July 16th Nuclear Explosion-Safety and Monitoring of Personnel (U). Los Alamos Scientific Laboratory, Atomic Energy Commission. Los Alamos, NM.: LASL. LA-616. January 9, 1947. 170 Pages.***

2. Bainbridge, K. T. Memorandum to All Concerned, Subject: TR Circular No. 18--Total Personnel at TR. [Base Camp, Trinity Site: NM.] July 3, 1945. 1 Page.**

3. Bainbridge, K. T. TRINITY. Los Alamos Scientific Laboratory. Los Alamos, NM.: LASL, LA-6300-H and Washington, D. C.: GPO. May 1976. 82 Pages.**

4. Bramlet, Walt. Memorandum for Thomas J. Hirons, Subject: DOD Participants in Atmospheric Tests, wo/encl. Los Alamos Scientific Laboratory. Los Alamos, NM. ISD-5. February 20, 1979. 4 Pages.**

5. General Electric Company--TEMPO. Compilation of Local Fallout Data from Test Detonations 1945-1962. Vol. 1: "Continental US Tests." Washington, D. C.: Defense Nuclear Agency. DNA 1251-1(EX.). 1979. 619 Pages. (A99) AD/AO79 309.*

6. Groves, Leslie R., LTG, USA. Memorandum for Secretary of War, [Subject: TRINITY]. [Washington, D.C.] 18 July 1945. 13 Pages.**

7. Groves, Leslie R., LTG, USA (Ret.). Now It Can Be Told: The Story of the Manhattan Project. New York, NY.: Harper and Row. 1962. 444 Pages.

8. Headquarters, 9812th Technical Service Unit, Provisional Detachment No. I (Company "B"). [Extract from: Daily Diary, Provisional Detachment No. 1 (Company "B"), 9812th Technical Service Unit.] Army Corps of Engineers, Department of War. [Santa Fe, NM.] 14 July 1945. 2 Pages.**

9. Headquarters, Special Service Detachment. Supplemental Special Guard Orders, with Appendix. Los Alamos Scientific Laboratory, Manhattan Engineer District. [Alamogordo, NM.] 14 July 1945. 4 Pages.**

10. Hempelmann, L. H., M.D. [Extracts from: "Preparation and Operational Plan of Medical Group (TR-7) for Nuclear Explosion 16 July 1945."] Los Alamos Scientific Laboratory, Atomic Energy Commission. Los Alamos, NM.: LASL. LA-631(Deleted). June 13, 1947. 32 Pages.***

11. Hoffman, J. G. [Extracts from "Health Physics Report on Radioactive Contamination throughout New Mexico Following the Nuclear Explosion, Part A--Physics."] Los Alamos Scientific Laboratory, Manhattan Engineer District. [Los Alamos, NM.] [1945.] 31 Pages.**

12. Lamont, Lansing. Day of TRINITY. New York, NY.: Atheneum. 1965. 331 Pages.

13. Los Alamos Scientific Laboratory, Public Relations Office. "Los Alamos: Beginning of an Era, 1943-1945." Atomic Energy Commission. Los Alamos, NM.: LASL. 1967. 65 Pages.**

14. Oppenheimer, J. R. Memorandum for Group Leaders, Subject: TRINITY Test. Los Alamos Scientific Laboratory. Los Alamos, NM. June 14, 1945. 2 Pages.**

15. Palmer, T. O., Maj., USA. Evacuation Detachment at TRINITY. [Manhattan Engineer District, Army Corps of Engineers.] [Los Alamos, NM.] [18 July 1945.] 2 Pages.**

16. Reynolds Electrical & Engineering Company, Inc. [Personnel Radiation Exposures, 1945, 1946] Las Vegas, NV. Microfilm.****

17. Warren, S. L., COL., USA. Directions for Personnel at Base Camp at Time of Shot. Los Alamos Scientific Laboratory, Manhattan Engineer District. [Alamogordo, NM.] 15 July 1945. 1 Page.**

18. Warren, S. L., COL, USA; Hempelmann, L. H., M.D. Extracts from: Personal Notes, Subject: Events in Camp Immediately Following Shot--July 16, 1945. 1945. 2 Pages.**

19. Weisskopf, V.; Hoffman, J.; Aebersold, Paul; Hempelmann, L. H. Memorandum for George Kistiakowsky, Subject: Measurement of Blast, Radiation, Heat and Light and Radioactivity at Trinity. [Los Alamos, NM.] 5 September 1945. 2 Pages.**